void setup() {
  // put your setup code here, to run once:
  pinMode (13, OUTPUT);
  pinMode (12, OUTPUT);
  pinMode (11, OUTPUT);
  
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite (12, HIGH);
  digitalWrite (11, LOW);
  digitalWrite (13, HIGH);
  delay (1000);
  digitalWrite (13, LOW);
  delay (500);
  digitalWrite (12, HIGH);
  digitalWrite (11, LOW);
  digitalWrite (13, HIGH);
  delay (1000);
  digitalWrite (13, LOW);
  delay (500);
  
}